Matching a wick to a candle's diameter
Shows how to measure a candle and read the wick size guidance without guessing.
This note shows how to measure a candle and read a wick size chart without guessing. You get a fixed measuring method, a way to test the choice, and a list of signs that the wick is wrong for the candle. The chapter on choosing a wick covers the full selection and fixing method, and this page covers only the measuring step.
What you need
- A rule marked in millimetres
- A strip of stiff paper about 2 cm wide and longer than the candle is around
- A pencil and a notebook
- The finished candle, or the mould it will be poured into
Measure the diameter
- Find the widest point of the candle across its centre. Diameter is the full width from one side to the other, not the distance from the centre to the edge.
- Wrap the paper strip once around the candle at the middle height. Mark where the paper overlaps, then lay the strip flat and measure the length to the mark.
- Divide that length by 3.14 to get the diameter. A strip of 31.4 cm around a candle gives a diameter of 10 cm.
- For a mould, measure the inside width at the top, where the flame will sit. Record the width at the bottom too. A wide gap between the two means the mould tapers, and the top figure is the one to use.
- Repeat the measurement at two other heights. Write down the smallest and largest readings. If they differ by more than a few millimetres, the candle is not a true cylinder, and the wick must suit the widest reading.
Read the wick guidance
Wick charts give a wick size for a range of diameters. Charts differ between makers and between waxes, so a chart is a starting point, not a rule. Read the row that contains your measured diameter, then check the wax type printed on the chart against the wax you use. If the two do not match, expect to test.
| Measured diameter | Starting point | Sign the wick is too small | Sign the wick is too large |
|---|---|---|---|
| Under 3 cm | Smallest braided wick on the chart | Pool stops short of the edge, flame is weak | Flame leans, smoke, a tall flame that flickers |
| 3 cm to 6 cm | Middle wick on the chart | Tunnel forms, wax left at the rim | Wide pool, soot on the glass or wall of the container |
| Over 6 cm | Largest wick on the chart, or two wicks where the chart allows | Hollow centre, wick drowned in pool | Flame too tall, rapid pool, heat marks on the surface |
Test before you commit
A test burn shows the match better than any chart. Light the candle on a flat, heat-resistant surface and let it burn for about one hour. Look at the pool at the end of that time. A good match forms a pool that reaches the edge, with a steady flame about as tall as the wick is thick.
Terms used here
- Diameter
- The full width of a candle across its centre, measured in millimetres or centimetres.
- Melt pool
- The shallow layer of liquid wax that forms at the top of a burning candle.
- Tunnelling
- A hollow that burns down the centre of a candle, leaving a rim of unmelted wax. It is caused by a wick too small for the diameter.
- Mushrooming
- A dark ball of carbon that builds on the tip of the wick. It is caused by a wick too large for the diameter or by a flame that is too high.
Write the diameter, the wick chosen and the result of the test burn in your notebook. Over several candles, the notebook becomes a record for your own wax and containers, and it is more reliable than any single chart. For how these notes are dated and arranged, see About the site.